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Isolating Issues in Mac OS
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Startup Manager: How to select a startup volume
Troubleshooting: My computer won't turn on
If your Macintosh computer won't turn on, here's how to troubleshoot it. Please keep in mind that although your computer may display similar symptoms that prevent it from showing video, this article discusses what to do if the computer won't turn on, meaning that when you press the power button:
- You don't hear a startup chime.
- You don't hear any fan or drive noise.
- The power button or power indicator doesn't light up at all.
If your computer doesn't display any video, it may display one or more of these similar symptoms when you press the power button:
- You may hear a startup chime.
- You may hear fan or drive noise.
- You may see the power button or power indicator light up.
If any of these conditions occurs, see Troubleshooting: My computer has no video instead.
If your computer won't turn on, try each of these steps:
- Make sure that the power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. (To check if the wall socket is working, plug in a lamp or other electrical device.)
- Make sure that the power adapter is properly connected to the power port on the side or back of the computer.
- Disconnect all accessories that are plugged into the computer, such as a printer, hub, or other mobile device.
- Reset the computer's PMU, SMC, or PRAM. Refer to the instructions for your model:
reset SMC For "Mac wont' turn on or boot" and related
General purpose Mac troubleshooting guide: Isolating issues in Mac OS X
Creating a temporary user to isolate user-specific problems: Isolating an issue by using another user account
Identifying resource hogs and other tips: Using Activity Monitor to read System Memory and determine how much RAM is being used
Starting the computer in "safe mode": Mac OS X: What is Safe Boot, Safe Mode?
To identify potential hardware problems: Apple Hardware Test
General Mac maintenance: Tips to keep your Mac in top form
First, if at all possible make a backup of the drive in its present configuration. If something goes wrong during repair attempts and makes things worse you will have a backup. You will have to decide how to work this in the light of any present backups you may have, for example, a backup that may be a few days out of date. In that case you may want to keep that one and make a second backup of this as they are now, though I realize people often don't have a lot of empty drives sitting around.
Boot from the System Installer disc that came with your computer or is the one for the version you currently have on there, select language if applicable, choose utilities, run Disk Utility and verify (and repair if necessary) the drive. You can verify a drive from DU on your main drive while booted but I have found this can result in incorrect reporting of errors. To repair your drive you have to run it from a drive other than the boot drive anyway.
Next, boot from your drive in Safe Mode (http://docs.info.apple.com/article.html?artnum=107393) and repair permissions. You can repair permissions while booted from the installer disc but this uses the permissions configuration on the installer disc which may be out of date if you have run any updates on your computer. Booting your computer to Safe Mode restricts the number of things running on your computer while permissions are being run and does a bit of spring cleaning at the same time.
Resolve startup issues and perform disk maintenance with Disk Utility and fsck - http://docs.info.apple.com/article.html?artnum=106214
Using Disk Utility in Mac OS X 10.4.3 or later - http://docs.info.apple.com/article.html?artnum=302672
Disk Utility's Repair Disk Permissions 10.0-10.6 - http://docs.info.apple.com/article.html?artnum=25751
"Try Disk Utility" (modified from http://support.apple.com/kb/TS1417)
1. Insert the Mac OS X Install disc that came with your computer (Edit: Do not use this disc if it is not the same general version as what you have currently on your computer, e.g. use a Tiger disc for a Tiger drive, not a Panther disc), then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk."
Then boot in Safe Mode, (holding Shift key down at bootup; takes longer to boot this way so be patient), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.
Mac OS X: Starting up in Safe Mode - http://docs.info.apple.com/article.html?artnum=107393
What is Safe Boot, Safe Mode? (Mac OS X) - http://support.apple.com/kb/HT1564
Safe Boot takes longer than normal startup - http://docs.info.apple.com/article.html?artnum=107394
Mac OS X 10.4, 10.5- Computer shuts down during Safe Boot - http://support.apple.com/kb/TA24054
If you don't have an installer disc available you can try effecting repairs using fsk in Single User Mode - http://docs.info.apple.com/article.html?artnum=106214.
Post by japamac about using fsk - http://discussions.apple.com/thread.jspa?threadID=1649143
Repairing permissions in Single User Mode - http://discussions.apple.com/message.jspa?messageID=7117122
Mac Running Slow: General Tips & Advice (Kappy)